<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>location地址栏对象</title>
    <style>
        p{
            text-align: center;
        }
        span{
            color: red;
        }
    </style>
</head>
<body>
<p>
    注册成功！<span id="time">5</span>秒之后自动跳转到首页...
</p>
</body>
<script>
    //1.定义方法。改变秒数，跳转页面
    let num = 5;
    function showTime() {
        num--;
        if (num <= 0) {
            location.href = "index.html";
        }
        let span = document.getElementById("time");
        span.innerHTML = num;
    }
    //2.设置循环定时器，每1秒钟执行showTime方法
    setInterval("showTime()",1000);
</script>
</html>